Purkinje cells (PCs) in the cerebellum are particularly
vulnerable to damage caused by alcohol exposure during early brain development.
It is unknown how neuronal circuit interactions are altered during alcohol
exposure and how neurons that survive the insult of alcohol manage to compensate
for the loss of a significant number of PCs. In order to investigate the damage
on cerebellar circuits caused by developmental alcohol exposure, we will use a
rat model of fetal alcohol spectrum disorder (FASD), which mimics the
deleterious effects on the fetus caused by alcohol ingested by a pregnant mother
during the third trimester.

Because PCs are the sole output of the cerebellar cortex, we
hypothesize that a disruption in coordinated activity among PCs is the leading
cause of cerebellar dysfunction in the FASD model. This hypothesis is being
tested using a combination of sophisticated electrophysiological and imaging
techniques where it is possible to record multiple neurons simultaneously and
characterize the spatiotemporal propagation of their activity. Our main goal is
to elucidate the impact of alcohol exposure on cerebellar network processing in
the FASD model.

We will test the hypothesis that the PC synchronized activity is
impaired in the FASD model. In particular, we will test whether PCs which
survive the alcohol treatment exhibit an altered synchronized activity caused by
a change in GABAergic synaptic transmission and the delayed
hyperpolarization-activated current (Ih). These experiments will be performed
using multiunit extracellular loose-patch and intracellular whole-cell patch
clamp recordings. The mechanisms and degree of synchronized activity will be
analyzed as a function of distance between PCs.

We will also test whether the spatiotemporal population activity
of PCs is altered in the FASD model by performing neuronal population recordings
using ultrafast imaging of cerebellar slices that have been labeled with
voltage- and calcium- sensitive dyes. Moreover, we will test the hypothesis that
disruption in neuro-plasticity at the level of the synapses is altered in the
FASD model. For these experiments, we are using another combination of
techniques such as immunofluorescence, confocal microscopy and 3D-reconstruction
for quantitative analysis in fixed tissues, as well as dynamic visualization of
axons and spines in live cerebellar slices.

The results of this study are expected to provide a
break-through in our understanding of the functioning of homeostatic neuronal
circuits altered by alcohol exposure. This knowledge is necessary to
conceptualize and identify appropriate interventions to alleviate the brain
damage induced by developmental alcohol exposure. This project is very important
for public health because it will enhance our understanding of the fundamental
mechanisms of developmental alcohol effects on cerebellar control of motor
movement. It also raises the awareness of the general population about the
detrimental effects of alcohol and drugs of addiction on brain networks.